"These people were probably well down the track to developing type 1 diabetes," he says. "And the flu illness has acted as the final straw that broke the camel's back."

While the virus could have stimulated the autoimmune destruction of insulin producing cells, Chisholm says it could also have triggered insulin resistance, which reduces the body's response to insulin.

Chisholm says viral diseases could trigger other autoimmune diseases but the effect would be less noticeable.

Test results in the wings

Howard says he is yet to get test results back to confirm his suspicions that influenza A played a role in the current peak of type 1 diabetes cases.

He says a whole range of environmental factors that affect the immune system are being investigated as possible contributing factors.

Howard is investigating whether cows' milk help children to develop the condition.

Type 1 diabetes affects about 130,000 Australians and the incidence is increasing by about 3% a year.

One popular theory for the increase is the 'hygiene hypothesis', which suggests excessive cleanliness results in an over-reactive immune system that ends up attacking the body's own tissue.